Heat-insulated wall and tank construction



y 14, 1964 c. D. DOSKER 3,140,515

HEAT-INSULATED WALL AND TANK CONSTRUCTION Filed March 14, 1957 2 Sheets-Sheet 1 AH COVER\ H Z l l H it I J: :M/ \//\V J/ l5 w IO G-l3a I I I w l.Ill I CORNE osKR July 14, 1964 c. D. DOSKER 3,140,515

HEAT-INSULATED WALL AND TANK CONSTRUCTION Filed March 14, 1957 I 2 Sheets-Sheet 2 United States Patent 3,140,515 HEAT-INSULATED WALL AND TANK CONSTRUCTION Cornelius D. Dosker, Louisville, Ky., assignor to Conch International Methane Limited, Nassau, Bahamas, a

corporation of Bahamas Filed Mar. 14, 1957, Ser. No. 646,001 4 Claims. (Cl. 20-4) The present invention relates to containers for storing extremely low temperature liquid and, more particularly, to bulk storage containers for cold liquefied gases rang-- ing downwardly to sub-zero temperatures as low as minus 320" F. or less.

Low temperature liquid storage containers necessarily comprise: (1) a relatively thick heat insulating wall forming the floor and inner sides of the container; and (2) an outer reinforcing framework, usually of structural steel, cradling and supporting the insulating wall. In storing liquid nitrogen, for example, under normally encountered atmospheric temperature and pressure conditions, the insulating wall is subjected to a temperature gradient ranging from an atmospheric temperature of say 72 F. on the outside to a stored liquid temperature of say minus 320 F. on the inside. As a result, severe internal stresses are created within the insulation and these tend to rupture it and reduce its efiiciency. A pronounced reduction in efficiency will weaken the supporting structure by subjecting it to very low temperatures which cause embrittlement.

Because of the tendency to rupture, it is customary to store such liquid in an aluminum or other metal container which is placed within the insulated wall. This arrangement is undesirable because it involves a very substantial increase in the cost of an already expensive container as a whole.

The problem of constructing a satisfactory container for use in transporting liquefied gases is still more diflicult. This is particularly true of installations within the hull of seagoing vessels which, in the first place, should be relatively large, say on the order of 100 feet long, 50 feet wide and 50 feet high (100 l. x 40' w. X 50' h.), and, in the second place, should be integrally mounted on or secured to the hull of the vessel. The large size and integral mounting renders them very susceptible to damage as a result of the twisting and bending forces to which they are subjected as the ship rolls, pitches and hogs. As a consequence, attempts heretofore made to construct large size containers for the storage and trans portation of liquefied gases have not been marked with success.

The principal objects of the present invention are: to overcome in large measure the objections and disadvantages of prior low temperature liquid storage containers; to provide one which substantially reduces, if it does not entirely eliminate, the need of an inner metal tank; to provide one which is free to expand and contract along the inner face of the insulation as the thermal environment changes without setting up anything more than localized stresses which normally are incapable of rupturing the insulation; and to provide one which is characterized by expansion joints normally capable of accommodating the twisting and bending actions occasioned by outside forces such as the rolling, pitching and hogging of a vessel.

The foregoing objects, broadly speaking, are largely attained by: (1) providing a novel form of wall panel having front, back and perimetric side and end faces and dimensionally stable layers essentially composed of heat insulating material, the layers including a panel-type front layer, a structurally strong panel-type back layer and a relatively thick interposed block-type layer bonded to the ice front and back layers; (2) by securing the back layer of each panel to the wall supporting member independently of adjacent panels so that, when any panel of one wall is subjected to a relatively low temperature condition, its front layer may contract and move relatively away from the front layers of adjacent panels; and (3) by providing a liquid-impervious means forming a continuous liquidimpervious surface extending over the inner face of the wall formed by the panels, said means including expansion joint means cooperatively supported by adjacent panels in position to bridge the joint between panels along the front faces thereof.

With this novel type of panel, the various layers in it can be so designed that the interposed layer provides the major portion of the heat insulating effect required or desired, the back layer provides the structural strength required to enable each panel to be independently supported on the supporting structure while the front layer provides either or both (a) the structural strength required to control and minimize the degree of contraction of the interposed layer or (b) front face liquid-impermability of an order substantially reducing, if not eliminating, the penetration of the stored liquid into the panel. The individual and independent mounting of the panels tends to break up all stresses and strains into localized values which can readily be accommodated without damage. The expansion joint means has the advantage of permitting movement to accommodate contraction without leakage.

The invention is illustrated in the accompanying drawings wherein:

FIG. 1 is a fragmentary view of a ships hold constructed in accordance with the present invention, this view more or less schematically illustrating the relationship of the container to the hold of the ship;

FIGS. 2-4 are isometric views of corner-curb, floor corner-wall panels respectively;

FIG. 5 is a perspective view of a portion of one panel broken away to show its interior construction;

FIG. 6 is an enlarged fragmentary sectional view taken through the depth of a plywood panel such as is used to form front layers of each wall panel;

FIG. 7 is a fragmentary sectional view taken entirely through a panel to show how it is mounted upon a structural supporting framework or wall;

FIGS. 8-9 show the plug and cap which are used to close the corresponding recesses shown in FIG. 7;

FIG. 10 is an enlarged detail of the securing means used to secure the panel to the supporting structure;

FIG. 11 is a fragmentary view showing, in elevation, the relationship of the perimetric faces of a panel to the supporting structure;

FIG. 12 is an isometric view of a panel assembly comprising one corner-curb panel, two more curb wall panels, one on each side of the corner-curb panel, and one floor panel;

FIG. 13 is a perspective view of a weep plug used during the assembly of these panels into the container wall;

FIG. 14 is a fragmentary view of a pair of adjacent panels with a temporary spline projecting from the front face joint line between them;

FIG. 15 is a fragmentary view of two adjacent panels showing them with their opposed perimetric grooves filled with a sealing material; and

FIG. 16 shows a modified form of expansion means for the front face joint line between panels.

Outer Supporting Framework Any suitable framework may be employed so long as it is capable of cradling and supporting my improved form of container for storing extremely low temperature liquid. Since the container, illustrated in FIG. 1,

is mounted in the hull of a vessel, the outer framework may comprise: a conventional assembly 1 of structural metal members secured together to provide an openwork support for the outer shell 2 of the hull and for an inner metal shell 3, the inner face of which forms a sturdy backing surface for the wall panels. The assembly 1 cradles and supports the inner shell 3 while the inner shell 3 provides a sturdy support for the wall panels, which form the heat-insulating and liquid-retaining Walls of the container, and thereby cradles and supports the container itself.

CONTAINER-FORMING WALL PANELS In accordance with my invention a suitable number of panels is provided to form the four side walls and floor of the container. While these panels may be variously designed, shaped or fashioned, I prefer to provide: a horizontal succession of curb panels to form the entire horizontal periphery of the floor and the adjacent lower horizontal margin of all vertical walls, the curb panels including a corner-forming trihedral curb panel 5 at each vertical and bottom corner intersection of the container and a series of dihedral curb panels 6 for the curb space along the bottom corner between vertical corners; enough floor panels 7 to fill in the floor space encircled by the curb panels; and enough wall panels to build the vertical walls upwardly from the curb panels in tiers, each tier including an endless horizontal succession of wall panels composed of a series of side wall panels 7 for the wall space between vertical corners and a corner-forming dihedral wall panel 8 at each vertical corner of the container. The floor panels 7 and the wall panels 7 are preferably identical.

Structure of Panels Each panel comprises a rigid relatively thick structure having front, back and perimetric side and end faces and dimensionally stable layers essentially composed of heat insulating materials. These layers include: panel-type rear and front plywood layers 10 and 12, the rear layer being structurally strong and the front layer preferably being a hardwood plywood or other dense wood, the denser the better; and a relatively thick interposed blocktype layer 11 bonded to said front and back layers 12 and 10. These panels are distributed over the backing surface 3 with their back faces in adjacent face-to-face relationship with the backing and with their adjacent perimetric faces in close tight abutting relationship with each other at room temperatures.

Each panel preferably is square cut along all perimetric side and end faces except where special circumstance might otherwise require. Each panel also contains: a suitable number of fastening holes 13 extending from the margins of the front face straight through to the back face and being spaced inwardly from the adjacent perimetric face; a more or less centrally disposed pump hole 14 extending from the front face straight through to the back face; and one or more, preferably two, endless perimetric grooves 15 spaced from each other and from the front and back faces. Two perimertic grooves 15 are shown and these are located nearer the back face than the front face of the panel block.

As indicated in FIG. 6, the front plywood layer 12 is composed of an odd number of plys, preferably three, designated for front, c for center and r for rear. These plys are arranged in conventional cross ply fashion so that the front and rear laminates f and r have their grain lines running parallel to each other while the center ply c has its grain lines running at right angles to that of the front and rear plys or laminates. Furthermore the center ply is made thicker than the other plys and its thickness is such that the plywood layer will be temperature balanced.

By temperature balanced, I mean that the thermal contraction of the front and rear face plys, in the direc- 4 tion of their grain, is less than that of the center ply in the same direction but the face plys are strong enough to restrict the contraction of the center ply to that of the face plys in a direction parallel to the grain of the face plys. On the other hand, the thermal contraction of the center ply, in the direction of the length of its grain, is smaller than that of the face plys in the same direction. The center ply thickness, therefore, is made such, usually twice that of the face plys, that it can restrict the contraction of the face plys to that of the center ply in a direction parallel to the grain of the center ply.

The rear plywood layer 10 may also be a 3 ply layer temperature balanced in the same way as the front plywood layer. If desired, it may be impervious but this is not essential. It should normally be heavier than the front plywood layer. Thus in a panel say 6 long by 2 /2 wide by 1 thick (6 l. x 2 /2 w. x 1' t.), the rear plywood layer 10 may be say of an inch in thickness and the front plywood layer 12 may be and preferably is of a smaller value say /8 of an inch in thickness.

The interposed layer 11 of each panel may be constructed of any suitable slab insulation such as corkboard, wood fiber bonded together under heat and pressure, mineral wood bonded under pressure, etc. It should, of course, be dimensionally stable and should provide effective heat insulating properties. I have obtained very excellent results with an interposed layer built up of a light weight specie having good insulation properties and adequate strength. Thus, in FIG. 5, I show 6 balsa wood laminates, each composed of glue-bonded blocks or rods 'of rectangular cross section.

The laminates of the interposed layer 11 are crossplied also so that the grain runs in one direction in the odd numbered. laminates and at right angles thereto in the intermediate laminates. Preferably, the foremost laminate of the intermediate layer 11, has its grain lines running parallel to the grain lines in the adjacent laminate of the front plywood layer 12. In this way, when the front and intermediate layers 12 and 11 are bonded together, the bond will be between laminates having their grain lines parallel to each other. This arrangement is preferred because, as taught by US. Dosker Patent #2,413,9l2, granted Jan. 7, 1947, it provides a stronger bond than can be obtained when the grain lines of the bonded faces are at an angle to each other.

It will, of course, be understood that the laminates or layers of the panels will present exposed end grain at and along the perimetric faces of the panel. Consequently, when the panel is completed and its perimetric grooves 15 have been formed, the perimetric faces (of the front, rear and intermediate layers) should all be carefully coated with a sealant, such as an animal glue, so as to increase the resistance of the panel to liquid and gas penetration along its end grain. It will, of course, be appreciated that when the interposed layer is composed of laminates built up from short blocks glued together, the bonding glue used will cover every face of each block. This has the advantage of tending to localize to a given block, any gas or liquid which succeeds in entering the block.

If desired, the denser and stronger balsa wood may be used along the opposite faces of the intermediate layers and the less dense or more porous and mechanically weaker balsa wood toward the center thereof. By appropriate design of this character, one can increase the usable balsa wood obtained from a given tree from about 40 to 50% to as much as 70% of the total wood of the tree.

PANEL MOUNTING MEANS In accordance with an important feature of this invention, each panel is mounted on the supporting framework by securing the rear portion of the panel to the backing surface 3 leaving the rest of the panel free to contract and expand as it will both in relation to its own securing means and in relation to adjacent panels all without imposing any undue load upon the securing means other than the load imposed thereon by the weight of the panel. In mounting a panel on the backing surface 3, a Nelson stud 17 is inserted through the cap section a of fastening hole 13 and the adjacent plug section b thereof into the stud section and then more or less instantaneously welded to the backing surface 3 following the standard Nelson stud-welding technique. The space in section 0 around the stud 17 is now sealed with a suitable plastic compound 18, then a washer is placed over the stud and against the front face of the rear layer 10 and finally a nut 19 is threaded to the stud and used to draw the rear plywood layer 10 of the panel tightly against the backing surface 3.

While the a and b sections of the hole 13 remain unplugged until later, it may be noted that section b is ultimately intended to be closed by tapered plug 20 and section a by a cap 21. Preferably these parts are composed of material, the same as that removed from the panel in making sections a and b of hole 13. The plug 20 and cap 21 may, if desired, be dried to a moisture content lower than that of the material forming the walls of sections a and b and also machined to fit closely within those sections when thus dried. Under these conditions, the plugs will absorb moisture from the surrounding material and then expand into an extremely tight fit.

INSTALLATION OF PANELS While the panels may be installed in various ways involving various orders of installation, I prefer to install all curb panels first, all floor panels next and all wall panels last.

Curb Panels Installed The curb panels are installed to form an endless curb providing the outer marginal portion of the proposed insulating floor and, adjacent thereto, the lower marginal portion of each proposed insulating wall. This may be done as follows:

(a) Position a trihedral corner-forming curb panel at each corner, hydraulically jack or otherwise force it into tight engagement with the corresponding corner surfaces of the backing 3 and then, while holding it in place,

(1) Insert a Nelson stud 17 into each fastening hole 13 and weld it to the corresponding spot of the supporting member 3, i

(2) Break the porcelain around each stud,

(3) Fill the stud hole 130, surrounding each stud,

with mastic 18,

(4) Place a washer over the stud and against the front face of the back plywood layer 10, and

(5 Place nuts 19 on'the stud and tighten it to secure the insulating panel rigidly to the supporting structure 3.

(b) Caulk the installed trihedral curb panel 5, with caulking material 23 placed on and along all perimetric edges of its rear plywood layer as indicated in FIG, 11. The purpose of this caulking material is to seal the end grain of that layer and to place the caulking material 23 in position to seal the back portion of the joint line space between the side and end faces of the installed panel and the corresponding abutting faces of the panels to be later installed next adjacent to it.

(c) Position a dihedral or L-shaped curb panel 6 adjacent to a trihedral panel 5, hydraulically jack or otherwise force their adjacent perimetric side faces into very tight face-to-face contact wherein such abutting perimetric side faces cooperatively form a pair of verticallydisposed L-shaped perimetric passageways (extending from the upper or wall end of the panels vertically downward to near the bottom of the panels where they turn to extend horizontally to the toe or floor end of the curb panels), hold such contact while securing the panel (i.e., welding studs 17, breaking stud porcelain, sealing stud holes 130, applying washers and tightening panel securing nuts 19) and then caulk the exposed perimetric edge of its back plywood layer 10 with caulking material 23.

(d) Complete the curb wall from one corner panel 5 to the next corner panel 5 by repeating (c) for each successive dihedral curb panel 6 except the last panel which must be fitted into place with precision instead of force.

(e) Repeat (0) and (d) for each additional corner to corner curb wall.

It may be noted in connection with the panel mounting operation, designated (a) above, that a stud 17 may or may not be inserted into the pump hole 14. Preferably, one is inserted into that hole and secured, but the space around it is not sealed with mastic and the stud is not provided with a nut at this time. This pump hole 14 is kept available for a later operation of pumping mastic into the space between the back of the panel and the backing surface 3 of the supporting structure.

Floor Panels Installed The floor forming panels 7 of the container, required to cover the curb-enclosed space, may be instituted as follows:

(a) Position the first floor panel 7 in say the left rear corner, force it into a tight fit by hydraulic jack or other means so that its left and rear perimetric faces cooperate with the adjacent toe end faces of adjacent curb panels to form horizontally disposed L- shaped perimetric passageways 15 which interconnect with the vertically disposed L-shaped perimetric passageways 15 along each side face of the corner curb panel, perform the panel securing operations (i.e., weld the studs, break stud procelains, seal stud holes, apply washers and tighten stud nuts) and then caulk the exposed perimetric edges of its back plywood layer 10.

(12) Seal the L-shaped perimetric passageways as follows:

(1) Plug the front face joint lines, between the newly installed floor panel 7 and the corresponding curb panels 6 against perimetric passageway leakage by routing a groove into each front face along its joint lines and then plugging that groove with a tightly fitted temporary spline 24, as shown in FIG. 14,

(2) Insert a weep plug 25 into each exposed open end of all horizontal and vertical perimetric passageways 15 except the upper open ends of one vertical pair, and

(3) Attach a pump 26 to the unplugged open ends of the excepted pair of vertical perimetric passage.- ways 15 and pumping a sealant 27 into such passageways until all weep plugs extrude sealant through holes 25a in a manner visibly indicating that all passageways 15 are completely filled as indicated in FIG. 15.

(0) Install the next floor panel 7, say along the left curb and adjacent to the previously laid floor panel, as follows:

(1) Remove the weep plugs 25 which otherwise would be covered by the new floor panel 7, i

(2) Polsition, force fit, secure and caulk the new floor pane (3) Plug the front face joint lines, corresponding to the perimetric passageways which are to be sealed, by grooving such joint lines and plugging the grooves with temporary splines 24,

(4) Weep plug the exposed open ends of the perimetric passageways newly formed in the floor and of all interconnecting curb passageways except one pair, and

(5) Seal such passageways as before.

(d) Repeat (0) for all other floor panels 7 in the first row except the last panel, which must be fitted with precision instead of force.

(e) Install the second row of floor panels 7 adjacent the first row again proceeding from rear to front with one panel at a time following the floor panel installation technique heretofore outlined for the first and last panels of the row and also for all intermediate panels except:

(1) Since each newly positioned intermediate floor panel 7 cooperates with the previously installed floor panels adjacent to it to form two horizontally disposed L-shaped perimetric passageways, the sealing operation for the intermediate panels of the second row involves only plugging these passage ways at one horizontal end and pumping them at the other horizontal end.

(1) Repeat (e) for all other rows of floor the last row. (g) In installing the last row it should be noted (1) That all panels must be fitted with precision instead of force,

(2) That the horizontal perimetric passageways newly formed in the floor by all last row panels except the very last panel are U-shaped, hence should be weep pugged at both ends of the U and then sealed through an interconnecting curb perimetric passageway, and

(3) That the horizontal perimetric passageways newly formed by the very last panel of the row are endless, hence cannot be weep plugged but may nevertheless be sealed from the interconnecting perimetric passageways of the adjacent curb panels.

When the first floor forming panel 7 has been mounted as in operation (a) above, the perimetric passageways newly formed by it and those curb perimetric passageways which interconnect with it, are relatively short and may therefore be pumped full of a desirable sealant, even the heavy viscous ones, at operating pressures which are of relatively low or otherwise reasonable magnitude. It is because of this that the sealing of the perimetric passageways is instituted in operation (b) above.

While any suitable sealant may be employed the low viscosity resinous compositions, containing foaming additives, appear well suited for this. particular operation. These compositions are of a liquid nature when originally pumped into the passageways. Within the passageways they foam and cure in situ. The composition, particularly after foaming, not only fills the passageways but spreads out into the narrower spaces between abutting surfaces of the units. The cellular nature of the cured foamed material renders it an ideal barrier to heat transfer whether by conduction or by convection currents, and in addition, provides the passageway filler with ample resiliency and elasticity whereby it may yield in accordance with expansion and contraction of the units.

Wall Panels Installed All wall forming panels 7 and 8 of be installed as follows:

(a) Position a dihedral'corner-forming wall panel 8 at each corner, hydraulically jack, secure and caulk it in the same way as a trihedral corner-forming curb panel panels except the container may (b) Position a wall panel 7 adjacent to one corner wall panel 8, hydraulically jack, secure and caulk it and seal the vertically arranged L-shaped perimetric passageways it forms with the adjacent wall and curb panels by grooving and spline-plugging the front face joint lines, weep plugging the passageways and pumping them with sealant.

(c) Complete one side wall tier between two successive corner panels 8, by repeating (b) for each successive wall panel 7 except the last panel which must be fitted into place with precision instead of force.

(d) Complete one endless tier for all side walls by re peating (b) and (c) for each remaining side wall.

(2) Repeat (b), (c) and (d) for each endless tier additionally desired.

8 LIQUID INSULATING MEANS In further accordance with my invention, a liquid insulating means is provided to present a continuous liquid-impervious surface extending over the front faces of the panel and from panel to panel. This liquid-impervious means involves: a liquid-impervious material sealing the front face 12 of each panel and coextensive therewith; and an expansion joint means cooperatively supported by adjacent panels in position to bridge the joint line therebetween along the front faces thereof. The sealing material for the front face 12 of each panel may be in the form of a suitable compound applied to it as a surface coating or as an impregnant. Perferably, however, it is in the form of a liquid-impervious sheet covering the front face 12 and preferably bonded to it.

The expansion joint means preferably comprises: an inner expansion joint system; and an outer expansion joint system; each including an expansion joint line connection between each pair of adjacent panels along their front face joint lines and an expansion joint intersection connection at each groove intersection. The outer system additionally includes expansion means covering the bottom and vertical corners of the container where the panel structure is such as to provide a crack in its front face along the corner-forming areas. The inner expansion joint system may be omitted.

Completing Container In completing the container, a suitable asphaltic compound or other mastic is pressure pumped through pump hole 14 of each panel to fill all voids between the back face 10 of the panel and the adjacent face of the backing member 3. This pumping operation can be performed before or after the fastening holes 13 are closed with the wood plugs 20 and the plywood caps 21, which are glue bonded and sealed. At the conclusion of the pumping operation, a nut 19 may be placed on the stud 17 at the rear end of each pump hole and this part of the panel pulled tightly against the backing surface. Now each pump hole may be closed with a plug 20 and cap 21. It will, of course, be understood that the caps 21 are protected against liquid penetration in the same way as the face of the front layer 12 of each panel. Accordingly, the caps may be surface sealed or impregnated with a sealing compound or covered by a liquid-impervious disc bonded to the cap or by whatever liquid-impervious sheets cover the front face 12 as a whole.

CONTAINER IN OPERATION It will, of course, be understood that the container, when completed, will have an extremely tight connection at all panel joints under prevailing atmospheric temperature conditions. However, when the operation of filling the container with a liquefied gas, such as liquid nitrogen, is instituted, that portion of the liquid-impervious means, which is first covered by the liquefied gas, and the parts adjacent thereto (such as the front layers 10 of the appropriate panels and the expansion joint means therebetween) will immediately contract. For example, the front plywood layer of any such panel may be expected to contract in the direction of its length and width, say A to of an inch.

The interposed layer, being protected from quick contact with this tremendous cold will tend to contract more slowly than the front plywood layer. But the structurally stronger front plywood layer, will compel the adjacent portion of the interposed layer, which is bonded to it, to contract at the same rate and to the same extent. As the cold soaks into the panel the contraction of the interposed layer adjacent the front layer will tend to exceed the contraction of the front layer. Here again, the superior strength of the front layer will come into play ainst a degree of contraction exceeding that of the front layer,

One may expect the temperature of the rear plywood layers of two adjacent panels to remain at or near the ambient atmospheric temperature even when each panel is completely covered with liquefied nitrogen long enough to achieve stable temperature gradient. Accordingly, under these conditions, the panel should remain in relatively close abutting relationship along their rear layers while the contraction should be such as to space the front layers about /2" more or less, the spacing of their interposed layers progressively increasing from front to rear between the limits stated. With a contraction of this order it will be appreciated first that no undue strain is placed on the securing means; second that the outer and inner expansion joint line and intersection connection means should be able to accommodate the degree of contraction here involved without damage; and third that the degree of contraction along the perimetric grooves should be insuflicient to damage the heat seal that these two lines of sealant present between the joint space in front of them and that back of them.

It will also be apparent that the progressive manner in which this contraction takes place within the container, that is from the bottom of the container upwardly, should not occasion any damage since adjacent panels merely tend to pull away from each other while the flexibility of the materials used between panels should accommodate the differential in contraction which may occur in these areas.

Furthermore, when a ship bends, twists or hogs, the extent to which it is flexed adjacent a given panel is relatively small even when its overall fiexure is large. Consequently, any given panel is not apt to be pressed into contact with any adjacent panel except along the rear plywood layer and even here, the resiliency of such layers should be more than sufficient to accommodate this type of movement.

When the container is loaded, it may be covered by any suitable form of cover made of wood, fiber glass or even panels of the type herein proposed. As it gasifies, the gases may, if desired, be drawn off and once again liquefied.

It will be understood: that all exposed surfaces may be sealed to good advantage; that all sealants used are intended to prevent liquid and gas penetration is possible, otherwise to reduce each as much as possible; and that all bonding agents should be of low gas and liquid permeability at the low temperatures contemplated herein.

Modification of FIG. 16

In this modification the joint line groove is covered with a stainless steel, aluminum or other transversely expandible metal strip 68, the ends of which penetrate the front face layer 12 for anchoring purposes.

Having described my invention, 1 claim:

1. A heat insulating and liquid retaining wall of a container for storing extremely low temperature liquid comprising: a structural wall-supporting member providing a backing surface; a plurality of insulating panels of large dimension arranged in end-to-end and in sideby-sicle relation over said backing surface with their adjacent perimetric faces in substantially abutting relationship one with the other, each of said panels being formed in cross-section of a relatively thin back layer of high density and high structural strength, a relatively thin front layer of high density and high structural strength and an intermediate relatively thick layer of a highly porous insulating material bonded between the front and back layers to provide an integral structure; means securing the back layer of each panel to said wall-supporting member to support each of the panels from its back layer only and independently of adjacent panels so that, when the front layer of any panel of said wall is subjected to a relatively reduced temperatrue condition, its front layer may contract and move relatively toward and away from the front layers of adjacent panels and toward and away from the back layer of the same panel; and liquid-insulating means pro viding a continuous liquid-impervious surface extending over the front faces of the panels and from panel to panel, said liquid-insulating means being bonded to the front faces of said panels and including expandiblecompressible expansion-joint means cooperatively supported by the front layers of adjacent panels in position to bridge the joint therebetween along the front faces thereof.

2. The wall of claim 1 wherein: a securing stud projects from said backing surface; the back layer is formed with a hole for receiving said stud; a nut is threated to said stud to clamp the panel against said backing; and the stud hole space around said stud is sealed with mastic.

3. The wall of claim 1 wherein: caulking material seals the perimetric edge of the rear layer of a wall panel and the back portion of the joint space between the perimetric faces of said panel and an adjacent panel.

4. The wall of claim 1 wherein: each of the panels is formed with perimetric groves in the perimetric faces adjacent the back wall and in which the permetric groove on a perimetric face of one panel cooperates with the adjacent perimetric face of an adjacent panel to form a perimetric passageway; and sealing material fills said passageway.

References Cited in the file of this patent UNITED STATES PATENTS Re. 22,108 Crecca June 9, 1942 978,655 Sauerbeck Dec. 13, 1910 1,549,290 Broady Aug. 11, 1925 1,622,311 Fischer Mar. 29, 1927 2,020,630 Anderson Nov. 12, 1935 2,080,618 Madsen May 18, 1937 2,129,497 Horn Sept. 6, 1938 2,201,129 Weiland May 14, 1940 2,219,714 Sperry Oct. 29, 1940 2,235,230 Malarkey Mar. 18, 1941 2,339,865 Lurmour June 25, 1944 2,362,252 Ellinwood Nov. 7, 1944 2,414,628 Battin Jan. 21, 1947 2,428,325 Collins Sept. 30, 1947 2,505,903 Madger May 2, 1950 2,668,992 Klose Feb. 16, 1954 2,769,212 Hammitt Nov. 6, 1956 2,806,810 Beckwith Sept. 17, 1957 2,983,401 Murphy May 9, 1961 FOREIGN PATENTS 450,555 Great Britain July 21, 1936 OTHER REFERENCES Railway Age (publication), page 25, Dec. 9, 1944. 

1. A HEAT INSULATING AND LIQUID RETAINING WALL OF A CONTAINER FOR STORING EXTREMELY LOW TEMPERATURE LIQUID COMPRISING: A STRUCTURAL WALL-SUPPORTING MEMBER PROVIDING A BACKING SURFACE; A PLURALITY OF INSULATING PANELS OF LARGE DIMENSION ARRANGED IN END-TO-END AND IN SIDEBY-SIDE RELATION OVER SAID BACKING SURFACE WITH THEIR ADJACENT PERIMETRIC FACES IN SUBSTANTIALLY ABUTTING RELATION SHIP ONE WITH THE OTHER, EACH OF SAID PANELS BEING FORMED IN CROSS-SECTION OF A RELATIVELY THIN BACK LAYER OF HIGH DENSITY AND HIGH STRUCTURAL STRENGTH, A RELATIVELY THIN FRONT LAYER OF HIGH DENSITY AND HIGH STRUCTURAL STRENGTH AND AN INTERMEDIATE RELATIVELY THICK LAYER OF A HIGHLY POROUS INSULATING MATERIAL BONDED BETWEEN THE FRONT AND BACK LAYERS TO PROVIDE AN INTEGRAL STRUCTURE; MEANS SECURING THE BACK LAYER OF EACH PANEL TO SAID WALL-SUPPORTING MEMBER TO SUPPORT EACH OF THE PANELS FROM ITS BACK LAYER ONLY AND INDEPENDENTLY OF ADJACENT PANELS SO THAT, WHEN THE FRONT LAYER OF ANY PANEL OF SAID WALL IS SUBJECTED TO A RELATIVELY REDUCED TEMPERATURE CONDITION, ITS FRONT LAYER MAY CONTRACT AND MOVE RELATIVELY TOWARD AND AWAY FROM THE FRONT LAYERS OF ADJACENT PANELS AND TOWARD AND AWAY FROM THE BACK LAYER OF THE SAME PANEL; AND LIQUID-INSULATING MEANS PROVIDING A CONTINUOUS LIQUID-IMPERVIOUS SURFACE EXTENDING OVER THE FRONT FACES OF THE PANELS AND FROM PANEL TO PANEL, SAID LIQUID-INSULATING MEANS BEING BONDED TO THE FRONT FACES OF SAID PANELS AND INCLUDING EXPANDIBLECOMPRESSIBLE EXPANSION-JOINT MEANS COOPERATIVELY SUPPORTED BY THE FRONT LAYERS OF ADJACENT PANELS IN POSITION TO BRIDGE THE JOINT THEREBETWEEN ALONG THE FRONT FACES THEREOF. 